Neuroinflammation is an important mechanism of Alzheimer’s disease (AD)-associated neurodegeneration. Accumulation and deposition of Aβ around neurovasculature is found in the majority of AD patients. However, little is known whether Aβ deposition would result in chronic vascular inflammation and insufficiency, which may contribute to neurodegeneration. We showed previously that Aβ1-40 induces strong expression of inflammatory genes in primary cultured human brain endothelial cells (HBEC) by semi-quantitative RT-PCR analyses, including IL-1β, MCP-1, TNF-α, IL-8 and ICAM-1. In the present study, we have profiled cytokine expression at the protein level and shown that Aβ-treated HBEC secrete immunoreactive cytokines into media, including MCP-1, MCP-2, GRO, IL6, IL-8, etc. In order to determine whether these cytokines are expressed in AD brain, we have carried out real-time Q-PCR analyses using AD and age-matched nondemented control (ND) brain samples. Increased expression of inflammatory genes, IL-1β, MCP-1, IL-6, and GRO were observed in AD compared to ND brain samples. These results validate our findings in cultured HBEC. We next investigated transcriptional regulation of inflammatory genes in Aβ-treated HBEC. HBEC were treated with Aβ1-40 or scrambled Aβ40-1 for 8hr. Nuclear extracts were prepared and TranSignal Protein/DNA Array blots carrying 56 different transcription factors (TF) were used for the analyses (Panomics). Each TF was spotted four times on the blots and the experiments were repeated. In comparison with controls, five TFs were increased over two fold (AP-1, CREB, GATA, NFATc, GRE) and three TFs were down-regulated over two fold (p53, TR, MEF-1) in Aβ1-40-treated HBEC. Increased levels of AP-1, CREB and GATA were confirmed in AD brain samples by the same array analyses. Sequence analyses show that the promoter regions of many inflammatory genes carry AP-1 or/and CREB binding sites. GATA and NFATc are believed to complex or associate with AP-1 or/and CREB to regulate cytokine expression in cells. Our studies demonstrate that Aβ can induce inflammatory gene expression in HBEC and some of these genes are also up-regulated in AD brain and suggest that several TFs (AP-1, CREB, GATA or NFATc) may be involved in transcriptional regulation of the inflammatory genes in Aβ-treated HBEC and/or in AD brain.

Publication date

2006-07

Language

English

Affiliation

NRC Institute for Biological Sciences; National Research Council Canada